fix: add touch device detection for menu interaction - #9782

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="dashboard/src/components/chat/Chat.vue" line_range="823" />
<code_context>
     : "sse",
 );
+
+const isTouchDevice: boolean = window.matchMedia('(pointer: coarse)').matches;
+
 const transportOptions: Array<{ value: TransportMode; labelKey: string }> = [
</code_context>
<issue_to_address>
**issue (bug_risk):** On hybrid touchscreen devices whose primary pointer is reported as `fine` (for example, a laptop with both a mouse and touchscreen), `matchMedia('(pointer: coarse)')` returns false even when the user taps the screen. Both menus therefore disable click opening and rely on hover, but a touch tap does not produce the required hover event, so the Transport Mode and Language menus remain inaccessible.

**Triggers:** When a touchscreen device also has a fine primary pointer, or the available primary input changes after the component is initialized.

**Suggested fix:** Detect any available coarse pointer (for example, with `(any-pointer: coarse)` or `navigator.maxTouchPoints`) and keep the result reactive if the media-query match changes.
</issue_to_address>

Please address the comments from this code review:

## Individual Comments

### Comment 1
<location path="dashboard/src/components/chat/Chat.vue" line_range="823" />
<code_context>
     : "sse",
 );
+
+const isTouchDevice: boolean = window.matchMedia('(pointer: coarse)').matches;
+
 const transportOptions: Array<{ value: TransportMode; labelKey: string }> = [
</code_context>
<issue_to_address>
**issue (bug_risk):** `isTouchDevice` is a one-time snapshot of `matchMedia(...).matches`, so the menu interaction mode never changes after setup when the available primary pointer changes; attaching or removing a mouse/trackpad leaves the menus in the stale click-only or hover-only mode until the component is recreated or the page reloads.

**Triggers:** When a hybrid device changes its active or primary pointer during an open page session.

**Suggested fix:** Store the media query result in a reactive ref and update it from the `MediaQueryList` change event, removing the listener on component unmount.
</issue_to_address>